Phys.org July 19, 2024
Researchers at Texas A&M University conducted in situ tensile straining experiments to investigate the role of hydrogen and slip in crack initiation in nickel-based alloy 725. The experiments revealed no tendency for hydrogen to enhance localized slip and no necessity of slip for crack initiation. Using electrochemical charging introduced hydrogen into samples, melted extraction was used to measure hydrogen content. Image correlation analyzed localized plastic strains during in situ tensile tests. Cracks initiated both in regions with and without nearby localized slip. The fraction of cracks initiating with no nearby slip was greater at higher hydrogen content. They found that slip-assisted crack initiated generally occurred at locations where intergranular slip was arrested, especially at intersections of slipping coherent twin boundaries with thin twin lamellae. Cracks that initiated without nearby slip occurred at a wider variety of microstructural features, including inclusions, triple junctions, and surface flaws… read more. Open Access TECHNICAL ARTICLE
Crack initiation with and without nearby slip. Credit: SCIENCE ADVANCES, 17 Jul 2024, Vol 10, Issue 29